Tools used in the U.S. Seasonal Drought Outlook (SDO) included the official Climate Prediction Center (CPC) temperature and precipitation outlooks for February 2018 through April 2018 (FMA 2018), various short- and medium-range forecasts and models such as the 7-day quantitative precipitation forecast (QPF) totals from the Weather Prediction Center (WPC), the 6-10 day and 8-14 day CPC extended-range forecasts (ERFs), the weeks 3-4 outlooks from CPC, dynamical models at the seasonal time scale, the 384-hour total precipitation forecasts from several runs of the GFS, the 240-hour total precipitation forecasts from the ECMWF model, the 45-day total precipitation forecasts from the ECMWF ensemble, climatology for the FMA season including median soil moisture changes, initial conditions (the U.S. Drought Monitor valid January 15, 2018), and canonical climate anomalies associated with La Nina conditions.

In the Western Climate Region, drought intensified this past month across the western half of the Four Corners Region, with development occurring in western Utah and a swath across northeastern Oregon. Farther northeast, drought eased or was removed in central and eastern Montana. Further improvements are expected in Montana by the end of April, and removal is anticipated in Oregon. The odds favor above-normal precipitation in late January, and also for FMA as a whole, across the northern tier of states in the Western Climate Region. Farther south, forecasts the next two weeks and for FMA as a whole favor drier than normal weather in a swath across southern California, Arizona, and the southern tiers of Nevada and Utah. Drought is expected to persist there, with some northward expansion from southern California anticipated where conditions are already abnormally dry. In central Utah, the 3-month outlook favors neither dryness or wetness, but with no particularly heavy precipitation events on the horizon, and given how conditions have deteriorated and become more entrenched recently, persistence is likely there as well.

Forecast confidence for the Western Region is high except in central and northern Utah, where confidence is moderate.

In the High Plains Climate Region, February through April is a relatively dry time of year climatologically, but precipitation normals increase as the period progresses, and April is actually slightly wetter than the average month in a swath across the middle of the Region. Precipitation amounts look to be unremarkable through the rest of January, so the outlook is based on the longer-term indicators and climatology. For FMA 2018, there are enhanced chances for above-normal precipitation from the Canadian border southward through most of the Dakota. Improvement or removal is forecast there, but persistence is anticipated in the southern fringe of the drought area, where there are no enhanced chances for surplus FMA 2018 precipitation. Farther south, there are elevated chances of below-normal FMA 2018 precipitation in most of Colorado, the western half of Kansas, and adjacent Nebraska. Drought in and near these areas should persist, with some expansion into adjacent areas where initial conditions lean drier than normal, specifically central Colorado and a swath from central Kansas northward into southern Nebraska.

Forecast confidence for the High Plains Region is moderate to high except on the southern fringe of the northern Plains drought area, where confidence is low.

Consistent with the canonical La Nina signal, enhanced chances for subnormal FMA 2018 precipitation cover southern and western sections of the Southern Climate Region. In much of Oklahoma and the southern and western parts of Texas, the lsst half of January is a relatively dry time of the year, so even in areas were odds somewhat favor a wet end to the month, there should be no significant change in longer-term moisture deficits. Thus persistence is forecast for existing areas of drought there, and with mild dryness initially evident in southern and western Texas, drought is forecast to cover the southwestern two-thirds of the Lone Star State by end of April. On the other side of the Southern Climate Region, wetter than normal weather is forecast to prevail from from late January through the end of April, easing or removing drought from northeastern Arkansaa. For areas from eastern Texas and Oklahoma eastward through most of Louisiana, Arkansas, and Mississippi - between the relatively confident forecasts for persistence/development farther west and improvement/removal to the northeast - mixed or non-committal indicators make for a low-confidence forecast. Enhanced chances for above-normal precipitation exist for the end of January, but thereafter there is no tilt of the odds. Furthermore, climatological considerations aren't helpful, as the forecast period is not significantly drier or wetter than other times of the year. Persistence is the low-confidence forecast for this area for two reasons: First, above-normal temperatures are favored through the period, and above-normal temperatures would lead to a greater-than-average rate of surface moisture loss. Second, since the inception of the Drought Monitor, mid-January drought in this area has persisted through April slightly more often than it has improved.

Forecast confidence in the Southern Climate Region is moderate to high from southern Texas and central Oklahoma westward, and in northeastern Arkansas, but low elsewhere.

In the Midwest Climate Region, drought is restricted to portions of the middle Mississippi Valley. Forecasts favor above-normal precipitation in late January throughout the region, and odds similarly favor wetness for FMA 2018 in all but the small drought areas in north-central Missouri and south-central Iowa. Climatologically, the forecast period tends to bring slightly less precipitation than other times of the year. For these reasons, improvement or removal is forecast for most areas of drought, with a low-confidence persistence forecast in north-central Missouri and south-cental Iowa.

Forecast confidence in the Midwest Climate Region is low for north-central Missouri and south-central Iowa, and moderate to high elsewhere.

Existing drought is forecast to persist through the end of April in the Southeast Climate Region, with development anticipated in parts of Georgia and the Carolinas where marginally dry initial conditions are coincident with enhanced chances for subnormal FMA 2018 precipitation. Confidence, however, is reduced by odds that favor surplus precipitation through the end of January. A few late GFS and ECMWF model runs dropped heavy precipitation (between 2 and 5 inches) on parts of Alabama and west-central Georgia by the end of January, but taking model skill and consistency into consideration, along with the array of other indicators, existing drought still seems more likely to persist than improve, but no development is forecast, even where marginally dry initial conditions are coincident with enhanced chances of subnormal FMA 2018 precipitation.

Forecast confidence in the Southeast Climate Region is low Alabama and adjacent western Georgia, and moderate elsewhere.

Two areas of drought exist in the Northeast Climate Region; one covering central Maryland, and one in northeastern Pennsylvania. As in most of the central and eastern states, odds favor above-normal precipitation through the last half of January. There are snhanced chances for surplus precipitation to continue through the end of April in much of the Pennsylvania drought area, but not farther south. A warm February through April is favored throughout, with chances increasing farther south, where normals are also warmer. Overall, the preponderance of indicators favors drought removal in Pennsylvania, but persistence by a narrow margin in Maryland.

Forecast confidence for the Northeast Region is moderate in Pennsylvania, and low farther south.

In Hawaii, small areas of moderate drought exist in southwestern Kauai and the western half of the Big Island. La Nina conditions and the official CPC outlooks favor surplus precipitation for the forecast period statewide, and Hawaii is expected to be free from drought by the end of April. Currently, there is no drought in Alaska or Puerto Rico, and none is expected to develop.

Forecast confidence for Hawaii is moderate to high.

Forecaster: Rich Tinker

Next Seasonal Outlook issued: February 15, 2018 at 8:30 AM EST